Sulfadiazine (2-[paraaminobenzenesulfonamido]-pyrimidine), the pyrimidine analog of sulfapyridine, has been shown by Feinstone and his associates1 in their experiments with mice to be less toxic than either sulfapyridine or sulfathiazole. They found the drug to be readily absorbed into the blood and rapidly excreted in the urine. Higher concentrations were obtained with sulfadiazine than with equivalent doses of sulfapyridine or sulfathiazole. Long and his co-workers2 reported that sulfadiazine was less effective at equivalent concentrations than sulfathiazole in the treatment of experimental pneumococcic infections in mice. Osgood and Bullowa,3 using tissue cultures, found sulfadiazine to be only one-quarter as effective against pneumococci as sulfapyridine and sulfathiazole in equivalent concentrations.
Studies on the action of sulfadiazine in human beings have been reported by various investigators.4 With an associate we5 have previously reported on the pharmacodynamics of the drug in man. It is well absorbed from the gastrointestinal tract.